BMR means basal metabolic rate, the estimated calories your body uses at complete rest to keep essential functions running, such as breathing, circulation, and cell repair. It is not the same as total daily energy expenditure, which also includes activity and digestion.

There is no single good BMR number. BMR scales with lean mass, size, age, and sex. Typical adult values often fall roughly between 1,200 and 2,000 calories per day, but athletes with more muscle can run higher, and smaller or older adults can run lower.

BMR Calculator

Mifflin St Jeor · Harris Benedict · Katch McArdle · TDEE

Sex

Age

Height (ft)

Height (in)

Weight

lbs

Formula & activity

BMR Formula ?

Activity Level (for TDEE)

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BMR is calories at rest. Multiply by activity to estimate TDEE. Results are estimates, not medical advice.

⚡ Enter age, height, weight, and sex to estimate basal metabolic rate and daily calorie needs.

Basal Metabolic Rate

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TDEE Estimate

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Per Hour

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Formula

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BMR

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Mifflin St Jeor

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Harris Revised

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Harris Original

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Katch McArdle

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Lean Mass (est.)

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Cal / kg

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BMR share of estimated TDEE

BMRActivity + TEF

Step by step

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Estimated Daily Calories by Activity

📋 Activity Multipliers

Activity	Factor	TDEE	vs BMR

BMR Formulas and Methodology

Basal metabolic rate estimates the energy your body uses at complete rest. Online BMR calculators apply predictive equations based on sex, age, height, and weight. They are planning tools, not diagnoses.

Mifflin St Jeor

Men: BMR = 10w + 6.25h − 5a + 5 Women: BMR = 10w + 6.25h − 5a − 161 w = kg · h = cm · a = age in years Example (man, 77 kg, 178 cm, 30 yr): 10×77 + 6.25×178 − 5×30 + 5 ≈ 1,738 kcal

Harris Benedict revised

Men: 88.362 + 13.397w + 4.799h − 5.677a Women: 447.593 + 9.247w + 3.098h − 4.330a Revised Roza and Shizgal coefficients update the 1919 original equations

Katch McArdle

BMR = 370 + 21.6 × lean body mass (kg) LBM = weight × (1 − body fat%/100) Example: 77 kg at 20% fat → LBM 61.6 kg → BMR ≈ 1,701 kcal

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Mifflin St Jeor is a strong default for most adults. Prefer Katch McArdle when you have a reliable body fat measurement.

Activity Table & FAQ

TDEE ≈ BMR × activity factor. These multipliers are planning estimates used widely in nutrition coaching. Actual needs vary with NEAT, training, and measurement error.

Level	Factor	Typical lifestyle
Sedentary	1.2	Desk work, little exercise
Lightly active	1.375	Exercise 1 to 3 days per week
Moderately active	1.55	Exercise 3 to 5 days per week
Very active	1.725	Hard exercise 6 to 7 days
Extremely active	1.9	Physical job or two a day training

Profile	Mifflin BMR
Woman 60 kg, 165 cm, age 25	≈ 1,340 kcal
Man 77 kg, 178 cm, age 30	≈ 1,738 kcal
Woman 70 kg, 170 cm, age 45	≈ 1,384 kcal
Man 90 kg, 183 cm, age 40	≈ 1,844 kcal

What is BMR?

Basal metabolic rate is the estimated calorie burn needed to sustain basic life functions at complete rest. It is lower than total daily calorie burn because it excludes walking, exercise, and digestion.

How do you calculate BMR?

Convert height and weight to metric, then plug sex, age, height, and weight into Mifflin St Jeor or another chosen equation. This calculator shows the substitution steps for the formula you select.

What is the difference between BMR and TDEE?

BMR is resting burn. TDEE is estimated total daily burn after multiplying BMR by an activity factor. Weight change planning usually starts from TDEE, not BMR alone.

How to Use This BMR Calculator

Select US or metric units, then enter sex, age, height, and weight. Choose a formula. Add body fat percent if you use Katch McArdle. Pick an activity level to see estimated TDEE. The hero number is your selected formula BMR in calories per day. Defaults load so a result appears immediately.

Compare all four equations in the metric grid. Use the activity table to see how daily needs rise as you move from sedentary to extremely active. Export the table if you want the numbers in a spreadsheet.

How to calculate BMR manually

1. Convert pounds to kilograms and inches to centimeters. 2. Choose Mifflin St Jeor unless you have a reason to use another equation. 3. Substitute weight, height, and age. 4. Round to a whole calorie. 5. Multiply by an activity factor for a TDEE estimate.

BMR for men and women

Sex specific constants exist because average body composition differs. At the same height, weight, and age, the Mifflin equation returns a higher BMR for men than for women because of the +5 versus −161 constant. Individual results still vary with muscle mass.

BMR by age

Every equation subtracts calories as age rises. That models the average decline in resting metabolism with aging. Resistance training and higher lean mass can offset part of that trend, which is why Katch McArdle can diverge when body fat is known.

If two adults share the same weight but different ages, the older adult usually shows a lower BMR in these equations even before activity is considered.

Common mistakes

Treating BMR as the calorie target for weight loss without adding activity
Mixing pounds with a formula that expects kilograms
Using Katch McArdle with a guessed body fat that is far off
Expecting lab precision from a population equation
Ignoring that illness, hormones, and medications can change real resting burn

When this calculator is useful

Use it to set a maintenance calorie starting point, compare formulas, or explain why two people of similar weight can need different calories. Pair it with the Calorie Calculator for macros, or the Body Fat Calculator before using Katch McArdle.

When this calculator may not be enough

It does not measure true resting metabolic rate. Pregnancy, very low body weight, some endocrine conditions, and extreme athletes may need clinical guidance. Children and teens need age appropriate tools rather than adult equations alone.

Limitations

Results are educational estimates based on published equations. They are not medical advice and should not replace care from a qualified clinician or registered dietitian.

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Informational only. Consult a healthcare provider for medical or nutrition decisions.

What is a good BMR?

A good BMR is one that matches your size and lean mass, not a fixed target. Many adults land between about 1,200 and 2,000 kcal per day, but that range is descriptive, not a prescription.

Which BMR formula is most accurate?

Mifflin St Jeor is often recommended for general adult use. Harris Benedict revised is still common. Katch McArdle can be better when body fat is measured well. Indirect calorimetry remains the clinical gold standard.

Is RMR the same as BMR?

Resting metabolic rate is closely related but usually measured under less strict conditions than true basal metabolic rate. Online calculators often use BMR equations as a practical stand in for resting needs.

Sources & References

Mifflin MD et al. A new predictive equation for resting energy expenditure in healthy individuals. Am J Clin Nutr. 1990. PubMed: pubmed.ncbi.nlm.nih.gov/2305711
NIH National Institute of Diabetes and Digestive and Kidney Diseases: Body Weight Planner context on energy needs: niddk.nih.gov
Harris JA, Benedict FG. A Biometric Study of Human Basal Metabolism. Proc Natl Acad Sci USA. 1918. PMC: ncbi.nlm.nih.gov/pmc/articles/PMC1091498